Media support

ABSTRACT

In one example, a media support with a continuous belt rotatable and suction cups lengthwise along the belt and in lines laterally across the belt to hold down a sheet of print media as the sheet is moved through a hold down area, a vacuum pump to supply vacuum to the suction cups. The vacuum control system is configured to close a supply of vacuum to all of the suction cups in the hold down area and then open the supply of vacuum sequentially to each of multiple lines of suction cups as each line enters the hold down area and then close the supply of vacuum sequentially to each of the multiple lines of suction cups as each line leaves the hold down area until all of the suction cups in the hold down area are closed.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation of U.S. application Ser. No. 15/918,959 filedMar. 12, 2018 which claims priority to E.P. application no. 17167310.6filed Apr. 20, 2017, each incorporated herein by reference in itsentirety.

BACKGROUND

Large format inkjet printers use vacuum tables to hold down foamboard,cardboard and other inflexible or semi-flexible print media. Highcapacity vacuum pumps are used to develop the hold down forces needed tokeep large sheets of such media flat during printing and drying.

DRAWINGS

FIG. 1 is a block diagram illustrating an inkjet printer implementingone example of a new media support system.

FIGS. 2 and 3 are plan and elevation section views, respectively,illustrating an example implementation for a media support system shownin the block diagram of FIG. 1.

FIG. 4 is a detail from FIG. 3.

FIGS. 5 and 6-8 are front and rear perspectives, respectively, of theexample media support system shown in FIGS. 2 and 3. FIGS. 6-8 showalternate lateral positions for vacuum control.

FIGS. 9-11 are front elevation details showing alternate lateralpositions for vacuum control, corresponding to the example in FIGS. 6-8.

FIG. 12 is a perspective detail showing one example vacuum controlsystem in the media support system shown in FIGS. 2-8.

FIGS. 13-16 are section details showing alternate rotational positionsfor vacuum control in the example media support system shown in FIGS.2-8.

FIGS. 17 and 18 are plan and elevation section views, respectively,illustrating another example implementation for a media support systemshown in the block diagram of FIG. 1.

FIGS. 19 and 20 are flow diagrams illustrating example vacuum controlprocesses, such as might be implemented in the media support systemshown in FIGS. 2-4.

FIG. 21 is block diagram illustrating one example of a processorreadable medium with vacuum control instructions, such as might beexecuted with a printer controller shown in FIG. 1.

The same part numbers designate the same or similar parts throughout thefigures. The figures are not necessarily to scale.

DESCRIPTION

Corrugated cardboard is widely used to make boxes. Although inkjetprinters can print high quality images on corrugated cardboard, it isdifficult to hold down corrugated cardboard flat during printing anddrying to produce high quality inkjet images. Consequently, special,more expensive corrugated boards are sometimes used for inkjet printing.A new print media support has been developed to hold down regular, lessexpensive corrugated cardboard flat for inkjet printing. The supportuses suction cups on a vacuum belt to help increase the hold down forcesapplied to corrugated cardboard and other print media compared to beltswith vacuum holes alone. In one example, a vacuum control systemsupplies vacuum selectively to the suction cups that are covered by theprint media as the suction cups circulate through the media hold downarea, to reduce leakage and thus enable the use of smaller capacityvacuum pumps to generate the desired hold down forces.

These and other examples described below and shown in the figuresillustrate but do not limit the scope of the patent, which is defined inthe Claims following this Description.

As used in this document: “and/or” means one or more of the connectedthings; and a “processor readable medium” means any non-transitorytangible medium that can embody, contain, store, or maintaininstructions and other information for use by a processor and mayinclude, for example, circuits, integrated circuits, ASICs (applicationspecific integrated circuits), hard drives, random access memory (RAM),read-only memory (ROM), and flash memory.

FIG. 1 is a block diagram illustrating an inkjet printer 10 implementingone example of a new media support system 12. FIGS. 2 and 3 are plan andelevation section views, respectively, illustrating one implementationfor a media support system 12 shown in the block diagram of FIG. 1.Referring to FIG. 1, printer 10 includes media support system 12 with amedia support 14 that includes a continuous loop belt 16 and suctioncups 18 on belt 16. System 12 also includes a vacuum pump or othersuitable vacuum source 20, a vacuum control system 22 to control thesupply of vacuum to suction cups 18, and a belt drive mechanism 24 tocirculate belt 16. Printer 10 includes a printing unit 26 to print to asheet of cardboard or other print media on support 14 and a dryer 28 todry ink or other imaging material on printed media. Printing unit 26 maybe implemented, for example, as an inkjet printhead assembly. Dryer 28may be implemented, for example, as a hot air dryer.

Printer 10 includes a controller 30 operatively connected to mediasupport system 12, printing unit 26, and dryer 28. Controller 30represents the processing and memory resources and the instructions,electronic circuitry and components needed to control the operativeelements of printer 10. In particular, controller 30 includes vacuumcontrol instructions 32 to control the supply of vacuum to suction cups18 through vacuum control system 22. Also, in this example, printer 10includes a sensor 34 to sense print media on support 14. Controller 30may use feedback from sensor 34 to help control the supply of vacuum tosuction cups 18.

Any suitable drive mechanism 24 may be used to circulate belt 16. Forexample, drive mechanism 24 may include a drive roller to turn the beltand idler rollers to keep tension in the belt. A motor is operativelyconnected to the drive roller to turn the belt at the direction ofprinter controller 30, directly or through a separate motor controller.

Referring FIGS. 2 and 3, in this example belt 16 is configured as fourindividual belts 16A, 16B, 16C, 16D arranged parallel to one anotherlaterally across a media support area 36, under printing unit 26 anddryer 28 in this example. Each belt 16A-16D circulates through an upperrun 38, collectively defining support area 36, and a lower run 40.Arrows 42 indicate the direction each belt moves through upper run 38.Arrows 44 indicate the direction each belt moves through lower run 40.In this example, belt drive mechanism 24 (FIG. 1) includes a singledrive roller 46 to turn all four belts 16A-16D simultaneously, and idlerrollers 48 to keep tension in the belts.

Suction cups 18 are arranged along the outer perimeter 50 of each belt16A-16D so that multiple suction cups are exposed simultaneously alongupper run 38 to hold down a media sheet 52 supported on the belts.Although sheet media is shown, examples are not limited to supportingsheet media, but may be used to support continuous web and othernon-sheet media. In this example, media sheet 52 does not cover the fullwidth of support area 36, defined by all four belts 16A-16B, and thus issupported on belts 16A, 16B, and 16C. As best seen in the detail of belt16B shown in FIG. 4, each suction cup 18 includes a port 54 throughwhich air may be evacuated from the suction cup. Each port 54 is alignedwith a hole 56 in the belt to connect the corresponding port to thevacuum control system. In the example shown, each suction cup 18 is adiscrete part affixed to the belt. In other examples, where suction cups18 are integral to the belt, each port 54 will be coextensive with thecorresponding hole 56.

FIGS. 5-16 illustrate media support system 12 in more detail. FIGS. 5and 6-8 are front and rear perspectives of system 12, respectively.FIGS. 9-11 are front elevation details showing alternate lateralpositions for vacuum control system 22 corresponding to FIGS. 6-8. FIG.12 is a perspective detail of vacuum control system 22 and FIGS. 13-16are section details showing alternate rotational positions for vacuumcontrol system 22.

Referring now to FIGS. 2-16, vacuum control system 22 includes vacuumchambers 58 immediately adjacent to the inner perimeter 60 along theupper run 38 of each belt 16A-16D. A slot 62 (FIGS. 4 and 12) in eachvacuum chamber 58 is aligned with holes 56 in each belt 16A-16D to allowair to be evacuated from each suction cup 18 through port 54 as thesuction cup moves over a vacuum chamber 58. Vacuum control system 22also includes conduits 64 that fan out from a central duct 66 to eachchamber 58. In the example shown in the figures, two ducts 66 supplyvacuum to corresponding groups 67 (FIG. 12) of chambers 58 throughconduits 64 along each belt 16A-16D to define a media hold down area 68(FIG. 13) within media support area 36. Each duct 66 is attached to avacuum source 20 (FIG. 5). Circumferential slots 70 in each duct 66connect conduits 64 to vacuum source 20.

As best seen in the sequence of FIGS. 13-16, each duct 66 is rotatableto open and close individual conduits 64 to control the supply of vacuumto suction cups 18 along each belt. Also, as best seen in the sequenceof FIGS. 6-8 and 9-11, each duct 66 is translatable to simultaneouslyopen and close all of the conduits 64 for one or more belts 16A-16D. Aseal 72 around each duct 66 inhibits vacuum leaks along eachcircumferential slot 70. Seals 72 are omitted from FIGS. 6-8 and 12 tomore clearly show other features of vacuum control system 22.

Control system 22 is configured to control the supply of vacuumcollectively to the suction cups among belts 16A-16D. FIGS. 6-8 and 9-11illustrate one example for controlling the supply of vacuum collectivelyto the suction cups among the belts. In this example, each central duct66 includes a group 73 of three slots 70 for belts 16A and 16B, a group73 of two slots 70 for belt 16C, and a single slot 70 for belt 16D. InFIGS. 6 and 9, ducts 66 are positioned translationally (laterally acrossthe hold down area) so that a circumferential slot 70 in each duct 66 isaligned laterally with the conduits 64 to every belt 16A-16D, to supplyvacuum to the suction cups on all four belts 16A-16D (when individualconduits are open), as indicated by flow arrows 74 in FIG. 9. In FIGS. 7and 10, ducts 66 are positioned translationally so that a slot 70 isaligned laterally to belts 16A, 16B and 16C, but not belt 16D, to supplyvacuum to the suction cups on three of the four belts (when individualconduits are open), as indicated by flow arrows 74 in FIG. 10. In FIGS.8 and 11, ducts 66 are positioned translationally so that a slot 70 isaligned laterally to belts 16A and 16B, but not belts 16C and 16D, tosupply vacuum to the suction cups on two of the four belts (whenindividual conduits are open), as indicated by flow arrows 74 in FIG.11.

Thus, each duct 66 functions as a valve to simultaneously open and closeall of the conduits in a group of conduits fanning out from the duct toone of the belts. In one example, the width of media 52 is preset andducts 66 are moved to the corresponding translational position beforeprinting begins. In another example, a sensor 34 senses the size ofmedia 52 entering the media support area to signal controller 30(FIG. 1) to move ducts 66, through control system 22, to thecorresponding translational position “on the fly” during a printingoperation.

In this example, control system 22 is also configured to control thesupply of vacuum individually to the suction cups on each belt 16A-16D.FIGS. 13-16 illustrate one example for controlling the supply of vacuumindividually to the suction cups on each belt. In FIG. 13, the leadingedge of media sheet 52 has reached sensor 34 (FIG. 3) to signalcontroller 30 (FIG. 1) to supply vacuum to media hold down area 68through control system 22. In FIGS. 14-16, ducts 66 are rotating in syncwith the leading edge of media sheet 52 moving through media hold downarea 68 to open each conduit 64 in sequence, to supply vacuum tochambers 58 and the corresponding suction cups 18 in hold down area 68,and then close each conduit 64 in sequence as the trailing edge of sheet52 passes by.

Each duct 66 functions as a valve to open and close each of the conduitsindividually in sync with the passing media so that a leading suctioncup is connected to the vacuum source and then a trailing suction cup isconnected to the vacuum source while the leading suction cup is stillconnected to the vacuum source. When the leading suction cup reaches theend of the hold down area, it is disconnected from the vacuum sourcewhile the second, trailing suction cup is still connected to the vacuumsource. Then, when the second, trailing suction cup reaches the end ofthe hold down area, it too is disconnected from the vacuum source. Thesequence continues with leading and trailing suction cups until themedia sheet is moved all the way through the hold down area.

Vacuum chambers 58, conduits 64 and the rotatable and translatablevacuum ducts 66 together function as a manifold to simultaneouslydistribute vacuum collectively to multiple groups of suction cups acrossthe width of multiple suction cup belts and individually to suction cupsalong the length of each of the belt, as described above with referenceto FIGS. 6-16.

In another example, shown in FIGS. 17 and 18, the suction cup belt isimplemented as a single belt 16 with multiple rows of suction cups 18.Also in this example, conduits 64 and ducts 66 are embedded in a supportstructure 76 that also functions as a seal to inhibit vacuum leaks alongcircumferential slots 70. For a single belt implementation such as thatshown in FIGS. 17 and 18, vacuum chambers 58, conduits 64 and therotatable and translatable vacuum ducts 66 together function as amanifold to simultaneously distribute vacuum collectively to multiplegroups of suction cups across the width of the belt and individually tosuction cups along the length of the belt.

In the examples shown, belt holes 56 and suction cups 18 are arrangeduniformly around each belt in a straight line. Other suitable lengthwisearrangements are possible. For example, it may be desirable in someapplications to vary the spacing between suction cups around each beltand/or to stagger the suction cups on each side of a center line aroundeach belt. Also in the examples shown, the spacing between the parallellines of suction cups is not uniform. Referring to the plan views inFIGS. 2 and 17, media sheet 52 is registered to the bottom of the mediasupport area (the right side in the direction the sheet moves throughthe media support area). The spacing between lines of suction cups maybe greater near the registration reference where even the narrowestsheet will cover the suction cups, as shown, and lesser away from theregistration reference to more easily accommodate sheets of increasingwidth.

The configurations for a vacuum control system 22 shown in the figuresare just examples. Other suitable configurations are possible. Forexample, more or fewer vacuum chambers 58, conduits 64, and/or ducts 66may be used to vary the size of the media hold down area and/or theconcentration of vacuum chambers within the hold down area. For anotherexample, other valve mechanisms may be used to open and close the supplyof vacuum to the suction cups.

FIG. 19 is a flow diagram illustrating one example of a vacuum controlprocess 100, such as might be implemented with a vacuum control system22 shown in FIGS. 2-18. Referring to FIG. 19, media entering a mediahold down area is sensed (block 102) and, based on the sensing, vacuumis supplied to individual suction cups along the length of a suction cupbelt as each suction cup passes through the media hold down area (block104). In one example, the supply of vacuum to each suction cup isinitiated when the suction cup enters the hold down area and ends wheneach suction cup leaves the hold down area.

FIG. 20 is a flow chart illustrating another example of a vacuum controlprocess 110, such as might be implemented with a vacuum control system22 shown in FIGS. 2-16. Referring to FIG. 20, media entering a mediahold down area is sensed (block 112) and, based on the sensing, vacuumis simultaneously distributed collectively to multiple groups of suctioncups across the width of one or multiple suction cup belts andindividually to suction cups along the length of the belt(s) (block114). In one example, vacuum is distributed collectively to multiplegroups of suction cups across the width of the belt(s) in block 114based on the width of the media entering the hold down area.

FIG. 21 is a block diagram illustrating one example of a processorreadable medium 78 with vacuum control instructions 32, such as might beexecuted with a printer controller 30 in FIG. 1. Vacuum controlinstructions 32 may include, for example, instructions to performprocess 100 shown in FIG. 19. Vacuum control instructions 32 mayinclude, for another example, instructions to perform process 110 shownin FIG. 20.

The examples shown in the figures and described above illustrate but donot limit the patent, which is defined in the following Claims.

“A”, “an” and “the” used in the claims means one or more. For example,“a continuous loop belt” means one or more continuous loop belts andsubsequent reference to “the belt” means the one or more belts.

1. An inkjet printer, comprising: an inkjet printhead assembly; and amedia support system comprising: a media support with a continuous beltrotatable in an endless loop past the printhead assembly and suctioncups arranged lengthwise along the belt and in lines laterally acrossthe belt to hold down a sheet of print media on the belt as the sheet ismoved through a hold down area near the printhead assembly; a vacuumpump to supply vacuum for the suction cups; and a vacuum control systemconfigured to close a supply of vacuum to all of the suction cups in thehold down area and then open the supply of vacuum sequentially to eachof multiple lines of suction cups as each line enters the hold down areaand then close the supply of vacuum sequentially to each of the multiplelines of suction cups as each line leaves the hold down area until allof the suction cups in the hold down area are closed.
 2. The printer ofclaim 1, comprising a sensor configured to sense a width of the sheetentering the hold down area and wherein the vacuum control system isconfigured to, based on the sensor sensing the width of the sheetentering the hold down area, close the supply of vacuum to suction cupslaterally outside the width of the sheet.
 3. The printer of claim 2,wherein the vacuum control system includes a manifold configured tosimultaneously supply vacuum collectively to multiple lines of suctionscups, the manifold adjustable, based on the sensor sensing the width ofthe sheet entering the hold down area, between a first position tosupply vacuum to shorter lines of suctions cups corresponding to anarrower sheet and a second position to supply vacuum to longer lines ofsuction cups corresponding to a wider sheet.
 4. The printer of claim 3,wherein the manifold comprises: multiple rows of multiple enclosures,each enclosure defining a vacuum chamber to underlay the belt; a linearslot along a top of each enclosure to align with holes in the belt; atubular duct; circumferential slots in the duct arranged to include atleast one group of multiple slots and at least one single slot; andmultiple conduits each extending between the duct and one of theenclosures; and wherein the duct is: translatable to align some or allof the conduits to a circumferential slot according to the translationalposition of the duct; and rotatable to connect some or all of thealigned conduits to a circumferential slot according to the rotationalposition of the duct.
 5. The printer of claim 4, comprising a sleevearound the duct to cover the circumferential slots when not aligned witha conduit.
 6. The printer of claim 1, comprising a dryer and wherein thebelt is rotatable in an endless loop past the printhead assembly andpast the dryer to hold down the sheet as the sheet is moved through thehold down area near the printhead assembly and near the dryer.
 7. Theprinter of claim 1, wherein the belt comprises multiple belts.
 8. Aprinting process, comprising: rotating a continuous belt in an endlessloop past a printing unit; selectively supplying vacuum to suction cupson the belt to hold down a sheet of print media as the sheet is movedthrough a hold down area near the printing unit, wherein the selectivelysupplying comprises: closing a supply of vacuum to all of the suctioncups in the hold down area; and then opening the supply of vacuumsequentially to each of multiple lines of the suction cups as each lineenters the hold down area, to hold down the sheet through the hold downarea; and then closing the supply of vacuum sequentially to each of themultiple lines of the suction cups as each line leaves the hold downarea until all of the suction cups in the hold down area are closed, torelease the sheet from the hold down area; and the printing unitprinting to the sheet in the hold down area.
 9. The process of claim 8,comprising: sensing a width of the sheet entering the hold down area;and based on the sensing, closing the supply of vacuum to suction cupslaterally outside the width of the sheet during the printing unitprinting to the sheet in the hold down area.
 10. An apparatus to holddown flexible sheets or webs flat for printing, comprising: a continuousbelt rotatable in an endless loop; suction cups arranged lengthwisealong the belt and in lines laterally across the belt to hold down asheet or web of print media as the print media is moved through a holddown area near the printing unit; a sensor configured to sense a widthof the print media entering the hold down area; a vacuum pump to supplyvacuum to the suction cups; and a vacuum control system configured to:based on the sensor sensing the width of the print media entering thehold down area, close a supply of vacuum to all of the suction cupslaterally outside the width of the print media; close the supply ofvacuum to all of the suction cups in the hold down area; and then openthe supply of vacuum sequentially to each of multiple lines of suctioncups as each line enters the hold down area; and then close the supplyof vacuum sequentially to each of the multiple lines of suction cups aseach line leaves the hold down area until all of the suction cups in thehold down area are closed.
 11. The apparatus of claim 10, wherein thevacuum control system includes a manifold configured to simultaneouslysupply vacuum collectively to multiple lines of suctions cups, themanifold adjustable, based on the sensor sensing the width of the printmedia entering the hold down area, between a first position to supplyvacuum to shorter lines of suctions cups corresponding to a narrowerprint media and a second position to supply vacuum to longer lines ofsuction cups corresponding to a wider print media.
 12. The apparatus ofclaim 11, wherein the manifold comprises: multiple rows of multipleenclosures, each enclosure defining a vacuum chamber to underlay thebelt; a linear slot along a top of each enclosure to align with holes inthe belt; a tubular duct; circumferential slots in the duct arranged toinclude at least one group of multiple slots and at least one singleslot; and multiple conduits each extending between the duct and one ofthe enclosures; and where the duct is: translatable to align some or allof the conduits to a circumferential slot according to the translationalposition of the duct; and rotatable to connect some or all of thealigned conduits to a circumferential slot according to the rotationalposition of the duct.
 13. The apparatus of claim 12, comprising a sleevearound the duct to cover the circumferential slots when not aligned witha conduit.
 14. The apparatus of claim 10, wherein the belt comprisesmultiple belts.